U.S. Pat. Nos. 5,539,029 and 5,811,477 disclose methods of preparing an asphalt emulsion-rubber paving composition comprising an aqueous asphalt emulsion, water, latex rubber and rubber particles. The rubber is mixed with other ingredients at ambient temperatures to form a homogenous liquid composition which is blended with aggregate at ambient temperatures to form a paving composition which provides a paving surface having improved skid resistance. The method and compositions described in the aforesaid patents are incorporated herein by reference. The methods described in the aforesaid patents result in improved paving compositions having very desirable properties including improved wet track abrasion and which are prepared without violating air pollution standards. The improved compositions incorporate polymer latex and reclaimed rubber particles in specific ratios. Although polymer latexes mix and perform well with a number of asphalts, when used with asphalts having a high acid number, some latex emulsions are unstable. Many latexes are mechanically unstable at any pH. Thus, the use of latexes in preparing compositions according to the aforesaid methods are problematic.
Asphalt emulsion compositions are prepared using polymer modified asphalt or a mixture of substantially water-free polymer and asphalt containing between about 1% and about 10% synthetic polymer by weight. An aqueous emulsion of the polymer/asphalt mixture is prepared and mixed at ambient temperature with rubber particles and/or particulate reclaimed rubber products in a ratio of synthetic polymer:rubber particles of between about 1:2 and about 1:20, by weight. The resulting compositions may also include one or more of gilsonite, added sulfur, a thickener, a surface active clay, carbon black, graphite, and fiber products. A paving composition is prepared by blending the resulting aqueous asphalt emulsion composition with aggregate and/or recycled asphaltic concrete particles. In a preferred embodiment a solids mix composition, preferably in the form of an aqueous slurry of the aforesaid components, without the aqueous asphalt emulsion and aggregate, is separately prepared, and then blended with the aqueous asphalt emulsion and with aggregate at ambient temperature. In an alternative embodiment, an asphalt mix composition comprising the polymer/asphalt blend, rubber and one or more of the additions may be prepared, and the mixture emulsified and then blended with aggregate.